1. Field of the Invention
The present invention relates to an internal gear pump capable of varying a discharge quantity of a fluid by causing an inner rotor to change a position of an outer rotor to which the inner rotor is brought into contact, with this internal gear pump capable of being easily manufactured and also capable of maintaining high product precision.
2. Description of the Related Art
Conventionally, there have been internal gear pumps that include an inner rotor and an outer rotor with which the inner rotor is brought into contact. As this kind of an internal gear pump, there exists a variable-capacity type internal gear pump that has an outer rotor having a rotation center at a position eccentric to a rotation center of an inner rotor which has a fixed position. The rotation center of the outer rotor moves along a locus of a circle of which a radius is the eccentricity to the rotation center of the inner rotor.
The variable-capacity type internal gear pump has a base line connecting between the rotation center of the inner rotor and the rotation center of the outer rotor. The base line rotates around the rotation center of the inner rotor.
There are various kinds of internal gear pumps that include such means for moving the outer rotor along a predetermined locus. The oil pump described in Japanese Patent Application Laid-open No. 2012-132356 is outlined below as an example. In the following description, reference numbers attached to members are those used in Japanese Patent Application Laid-open No. 2012-132356.
The oil pump described in Japanese Patent Application Laid-open No. 2012-132356 includes the adjusting ring 14 for moving the outer rotor 13 in a predetermined locus. At the casing 1 side of the oil pump, there are provided concave shape portions such as a guide groove, and convex shape portions including guide pins and protruded parts. The adjusting ring 14 moves along the concave shape portions and the convex shape portions via a moving means.